Method of correcting tilt in spectroscope

Abstract

In a rough adjustment step before spectroscopic analysis, a moving mirror is moved (# 1 ), the outputs of division elements when the interfering light of reflected light off the moving mirror and reflected light off a fixed mirror is received by a four-division sensor are totalized and variations in the contrast of the interfering light are detected (# 12 ), and, based on the variations in the contrast, the amount of relative tilt of the two reflected light beams is detected (# 13 ), and the initial tilt error is corrected (# 14 ). In a fine adjustment step before the spectroscopic analysis, based on a phase difference between the outputs of the division elements when the interfering light is received by the four-division sensor, the relative tilt amount of and the tilt direction of the two reflected light beams are detected, and the initial tilt error is corrected.

1 . A tilt correction method of correcting a tilt error between two reflected light beams, one of which is a light beam reflected off a moving mirror and the other is a light beam reflected off a fixed mirror in a spectroscope, the tilt correction method comprising steps of:
 correcting an initial tilt error of the two reflected light beams as an initial adjustment which is performed before a spectroscopic measurement; and   correcting a tilt error of the two reflected light beams caused by a movement of the moving mirror which is performed during the spectroscopic measurement;   wherein, the initial adjustment comprises a rough adjustment and a fine adjustment, and   in the rough adjustment, laser light is separated into two portions and the two portions are respectively guided to the moving mirror and the fixed mirror, and an interfering light of the two reflected light beams is, while the moving mirror is being moved, received by a four-division sensor, and outputs of division elements when the interfering light is received are totalized, and variations in contrast of the interfering light are detected, and
 based on the variations in the contrast, a relative tilt amount of the two reflected light beams is detected and the initial tilt error is corrected, and 
   in the fine adjustment, based on a phase difference between the outputs of the division elements when the interfering light of the two reflected light beams is received by the four-division sensor, the relative tilt amount of and a tilt direction of the two reflected light beams are detected, and the initial tilt error is corrected.   
     
     
         2 . The tilt correction method of  claim 1 ,
 wherein, in the fine adjustment, in a movement range that is one-tenth or less as wide as a maximum drive amplitude when the moving mirror is driven to be reciprocated, the relative tilt amount of and the tilt direction of the two reflected light beams are detected, and the initial tilt error is corrected.   
     
     
         3 . The tilt correction method of  claim 1 ,
 wherein, the relative tilt amount of and the tilt direction of the two reflected light beams are detected based on the outputs of the division elements when the interfering light of the two reflected light beams is received by the four-division sensor, and the tilt error of the two reflected light beams caused by the movement of the moving mirror is corrected.   
     
     
         4 . The tilt correction method of  claim 1 ,
 wherein a drive of the moving mirror during the spectroscopic measurement is a resonant drive.   
     
     
         5 . The tilt correction method of  claim 1 ,
 wherein the fixed mirror is driven to correct the tilt error.   
     
     
         6 . The tile correction method of  claim 5 ,
 wherein the fixed mirror is non-resonantly driven to correct the tilt error.   
     
     
         7 . The tilt correction method of  claim 6 ,
 wherein the fixed mirror is non-resonantly driven by expansion and contraction of a piezoelectric element.   
     
     
         8 . The tilt correction method of  claim 4 ,
 wherein the moving mirror is resonantly driven by a drive mechanism using a parallel plate spring.   
     
     
         9 . The tilt correction method of  claim 8 ,
 wherein a piezoelectric element is formed on a surface of at least one of two plate spring portions constituting the parallel plate spring, and   the moving mirror is resonantly driven by resonance of the two plate spring portions caused by expansion and contraction of the piezoelectric element.   
     
     
         10 . The tilt correction method of  claim 8 ,
 wherein a magnet is arranged in the parallel plate spring, and a coil is arranged separately from the magnet, and   the moving mirror is resonantly driven by resonance of the two plate spring portions caused by controlling a current passed through the coil.